Reinforcement Particle Size Research Articles

Effect of reinforcement volume fraction on mechanical alloying of Al–SiC nanocomposite powders

Mixtures of aluminium powder and nanoscaled SiC particles (n-SiC) at various volume fractions of 0, 1, 3, 5, 7 and 10 are comilled in a high energy planetary ball mill under an argon atmosphere to produce nanocrystalline Al–SiC nanocomposites. High resolution scanning electron microscopy (HRSEM), X-ray diffraction (XRD) method, laser particle size analysis and powder density measurement were used to study the morphological changes and microstructural evolution occurred during mechanical alloying. Al–SiC composite powder with microscaled SiC particles (1 m m) was also synthesised and characterised to examine the influence of reinforcement particle size on the milling process. It was found that with increasing volume fraction of n-SiC, a finer composite powder with more uniform particle size distribution is obtained. The morphology of the particles also became more equiaxed at shorter milling times. Furthermore, the analysis of XRD patterns by Williamson–Hall method indicated that the crystallite size of the aluminium matrix decreases with increasing reinforcement volume content while the lattice strain changes marginally. As compared with microscaled SiC particles, it appeared that the effect of n-SiC on the milling stages is more pronounced. The results clearly show that the reinforcement particles influence the work hardening and fracture of the metal matrix upon milling, affecting the structural evolution. With decreasing size of the ceramic particles to nanoscale, this influence becomes more pronounced as the surface to volume fraction increases.

Effect of Powder Size on Infiltration Height in Producing MgO Reinforced Al Matrix Composite by Vacuum Infiltration Method

The vacuum infiltration method is one of the composite producing methods. There are several parameters in composite production by vacuum infiltration. One of them is particle size of reinforcement in particulate reinforced composites. In this study, MgO powder and Al were used as reinforcement and matrix respectively. MgO powders with different size and amount to give same height were filled in quartz tubes and liquid metal was vacuum infiltrated into the MgO powder under same vacuum condition and for same time. Infiltration height was measured and microstructure and fracture behavior of composite were investigated. It has been found that infiltration height and fracture strength were increased with particulate reinforcement sizes. It has also been determined that molten metal temperature facilitates infiltration.

Effect of particle size ratio and particle clustering on sintering and stiffness of aluminium matrix composite

A metal matrix composite with a matrix composition of Al–3·8Cu–1Mg–0·75Si–0·5Sn was fabricated by sintering a particulate ceramic reinforcement with elemental metal powders. The sintering characteristics were examined as a function of reinforcement volume fraction, particle size and particle size ratio. At high volume fractions of reinforcement, densification ceased completely and the compacts expanded during sintering. Coarse reinforcement particles, not large particle size ratios, maximised the sintering response. Clustering of the ceramic was studied using Dirichelet tessellations of sintered microstructures. While clustering is evident in the sintered microstructures, it does not correlate to sintered density through the particle size ratio because the ceramic particles appear to rearrange in the presence of a large volume of sintering liquid. The effect of particle size is not due to clustering but maybe due to ceramic particle surface area.

Effect of microstructure on Young’s modulus of extruded Al–SiC composites studied by resonant ultrasound spectroscopy

In this work, an attempt was made to correlate the Young’s modulus of SiC particle reinforced aluminum alloy composites, measured by resonant ultrasound method, to reinforcement spatial distribution. Composites were fabricated by extrusion of billets that were previously formed using cold pressing blend of matrix alloy powders and ceramic particles. It has been shown that more aggregated microstructures were generated with an increase in ceramic volume fraction (to 20%) and the matrix alloy powder mean particle size from 40 to 180 μm as well as with a decrease in the reinforcement particle size (3–14 μm). At the same time, ultrasonic wave velocity as well as Young’s modulus diminish with a decrease in SiC content and its particle size, and with increase in matrix alloy particle size. The analysis showed that it could be partly attributed to the higher amount of residual porosity in agglomerated structures. An addition decrease of elastic characteristics was attributed to the increasing influence of mechanically imperfect contacts that formed between ceramic particles in the more aggregated microstructures.

Scalling effects on the deformation behaviour of W/Cu composite materials under dynamic loading

Tungsten/copper (W/Cu) particle composites were used to investigate the scaling effects on their deformation and fracture behaviour. The effects of the volume fraction and the particle size of the reinforcement (tungsten particles) were studied. W/Cu-80/20, 70/30 and 60/40 wt.% each with tungsten particle size of 10 and 30 μm were tested under compression loading up to high strain rates. Cylindrical compression specimens with different volumes (Do = H 0 ) were investigated with strain rates between 0.001s -1 and 6000 s -1 at temperatures from 20°C to 800°C. A clear dependence of the flow stress on the deformed volume of the specimens was shown for compression loading. An extensive metallographic investigation was carried out to determine a correlation between the deformation of the tungsten particles and the global deformation of the specimen. The contribution of the hard phase in the deformation process has shown to have an effective influence in the deformation process. The size of the deformed zone under compression loading showed an effect on the failure mechanism. The material behaviour of the different W/Cu composites was described with material laws. The parameters of the material law were presented as a function of the strain rate, temperature, the volume fraction and the particle size of the tungsten. The mechanical behaviour of the composite materials was numerically computed with the previously determined material laws.

Use of Artificial Neural Network for Prediction of Mechanical Properties of α-Al2O3 Particulate-reinforced Al–Si10Mg Alloy Composites Prepared by using Stir Casting Process

In this article, the tensile strength, hardening behavior, and density properties of different α-Al2O3 particle size (μm)-reinforced metal matrix composites (MMCs), produced by using stir casting process, are predicted by designing a backpropagation (BP) neural network that used gradient-descent learning algorithm. Artificial neural network (ANN) is an intelligent technique that can solve nonlinear problems by learning from the samples. Therefore, some experimental samples are prepared at first to train the ANN to provide (to estimate) tensile strength, hardening behavior, and density properties of the MMCs produced for any given α-Al2O3 particle size (μm). The most important point is that after the ANN has been trained using some experimental samples, it gives approximately correct outputs for some of the experimental inputs that have not been used in the training. First, to prepare the training and test (checking) set of the network, some results are experimentally obtained and recorded in a file on a computer. In the experiments, α-Al2O3 particles are supplied commercially. α-Al2O3 ceramic powder of a varying particle size of 10 vol% is prepared, and then this ceramic powder with different α-Al2O3 particle sizes is added to Al–Si10Mg alloy in melt condition by stir casting process. The effect of reinforced particle size on the tensile strength, hardness resistance, and density properties of α-Al2O3-reinforced MMCs have been investigated. Mechanical tests reveal that tensile strength and hardness resistance of the α-Al2O3 ceramic powder composites decrease with increasing reinforced α-Al2O3 particle size. Then, neural network is trained using the prepared training set, also known as the learning set. In the preparation of the ANN training module, the aim of the use of the model is to predict the tensile strength, hardening behavior, and density properties for any given α-Al2O3 particle size by using some experimental results. Different α-Al2O3 particle sizes (μm) are used as the input, and tensile strength, hardening behavior, and density properties are used as outputs in the neural network training module. The tensile strength, hardening behavior, and density properties of the produced MMCs are estimated for different α-Al2O3 particle sizes using neural network efficiently instead of time-consuming experimental processes. At the end of the training process, the test data are used to check the system accuracy. Simulation results confirm the feasibility of this approach and show a good agreement with experimental results for a wide range of MMCs produced.

Effect of reinforcement particle size on in vitro behavior of β‐tricalcium phosphate‐reinforced high‐density polyethylene: A novel orthopedic composite

Beta-tricalcium phosphate-reinforced high-density polyethylene (beta-TCP/HDPE) is a new biomaterial, which was made to simulate bone composition and study its capacity to act like bony tissues. This material was produced by replacing mineral component and collagen soft tissue of bone with beta-TCP and HDPE, respectively. The biocompatibility of composite samples with different volume fractions of TCP (20, 30, and 40 vol %) and two different particle sizes (80-100 and 120-140 mesh size) was examined in vitro using the osteoblast cell line G-292 by proliferation, alkaline phosphatase (ALP) production, and cell adhesion assays. Cell-material interaction on the surface of the composites was observed by scanning electron microscopy (SEM). The effect of beta-TCP particle size on behavior of the osteoblast cell line was compared between two groups of the composite samples containing smaller and larger reinforcement particle sizes as well as with those of a negative control. In general, results showed that the composite samples containing larger particles supported a higher rate of proliferation and ALP production by osteoblast cells after 3, 7, and 14 days of incubation compared to the composite samples with smaller particle size and control. Furthermore, more cells were attached to the surface of composite samples containing larger particle size when compared to the smaller particle size composites (p<0.05). This number was nearly equal with numbers adhered on negative control [tissue culture polystyrene (TPS)] and significantly higher in comparison with composite control [polyethylene (PE)] (p<0.05). Adhered cells presented a normal morphology by SEM and many of the cells were seen to be undergoing cell division. These findings indicate that beta-TCP/HDPE composites are biocompatible, nontoxic, and in some cases, act to stimulate proliferation of the cells, ALP production, and cell adhesion when compared to the control counterparts. Furthermore, beta-TCP/HDPE samples with larger reinforcement particle size were shown to possess better biological properties.

The Influence of Process and Material Variables on the Surface Properties of Polystyrene Matrix Reinforced with Silica Sand

The surface properties of polymer matrix composite materials reinforced with Jordanian silica sand and cement subjected to abrasive wear has been studied in this investigation. Process variables, such as velocity, load, and time and material variables, such as volume fraction of the reinforcement and particle size are studied using weight loss measurements. Wear mechanisms responsible for the observed variation in wear rate are also studied using a scanning electron microscope. It is concluded that the introduction of SiO2 hard particles significantly increases the abrasive wear resistance of polystyrene. The higher each of the process variables (load, velocity, and time), the higher the dimensionless wear rate, and the difference between the highest and the lowest wear rates decreases as the volume fraction content and the particle size increase. The higher each of the material variables (reinforcement content and particle size), the lesser the wear rate for fixed process conditions. It is also found that abrasive wear of SiO2-reinforced polymers occurs due to three wear mechanisms: microploughing, microcutting, and microcracking.

Spray processing of 2014-Al + SiC P composites and their property evaluation

Aluminium alloy (2014-Al alloy)-based metal matrix composites containing SiC P particulates were produced by spray co-deposition. The mass median diameter and mass flow rate of SiC P were varied from 6 to 30 μm and from 10 to 30 mass% of the melt flow rate respectively. Spray formed billets of 200 mm diameter and 400 mm height were produced. Porosity and SiC content were measured at different positions in the preform. The mass fraction of reinforcement incorporated in the preform varies from 6 to 15%. Porosity is observed to increase with the increase in the surface area of the reinforcement/matrix interface. Optical microscopy shows a uniform distribution of particulates. Smaller size particles are pushed towards the grain boundaries during solidification of the deposit, in contrast to their large size counterparts. The matrix grain size varies from 15 to 50 μm with the variation in size and content of reinforcement particles. The grain size of the matrix decreases with the increase in the SiC P content. This decrease in the grain size is more sensitive to the size of the reinforced particulates, i.e. smaller size particulates give rise to a better refinement. Microstructural examination of overspray powder particles shows that the collision of melt droplets and SiC particles is the major mechanism for the incorporation of small particles. The ageing behavior of composites was studied at different temperatures for various sizes and volume fractions of particles, and the mechanical properties were evaluated. Composites with smaller particulate size show an early hardness peak than those with larger size particulates. Composites reinforced with intermediate size of SiC P particulates show an increased elastic modulus compared to unreinforced alloy.

Properties of P/M processed particle reinforced metal matrix composites specified by reinforcement concentration and matrix-to-reinforcement particle size ratio

The effect of reinforcement particle size (3 and 14 μm), matrix-to-reinforcement particle size ratio (PSR) ranging from 2.9 to 12.9 and volume fraction of the reinforcement (0–20 vol.%) on microstructure and mechanical properties (yield stress, tensile strength, elongation to fracture and Young’s modulus) is investigated for Al–6Cu–0.4Mn⧹SiC p composites manufactured by the powder metallurgy route. A model is proposed to determine the critical reinforcement content for the composite at known PSR and to calculate the porosity and Young’s modulus of the material containing an excessive amount of the reinforcement.

Microstructure and electrical conductivity of Al-SiCp composites produced by spray forming process

Al- SiCp composites have been synthesized by spray forming process with variation in particle flow rate, size of reinforcement particles and their volume fraction. The microstructure of composites and their electrical conductivity have been investigated. The results showed a uniform dispersion of large size particulate phase in the matrix of the primary α- phase with its equiaxed grain morphology. However, clustering of small size particles was observed at the grain boundary and grain junctions. The grain size of the composite materials was observed to be lower than that of the base Al- alloy. The composite materials invariably indicated their lower electrical conductivity compared to that of the monolithic Al- alloy. The electrical conductivity of composites decreased with increase in the volume fraction and decrease in size of the reinforcement particles. A high flow rate of particles during spray deposition resulted in a decrease in its conductivity. These results are explained in the light of thermal mismatch between the matrix and the reinforcement phases resulting in generation of high dislocation density. The droplet- particle interaction and resulting microstructure evolution during the spray deposition of the composites are discussed.

Localized Corrosion Currents and pH Profile over B4C , SiC, and Al2O3 Reinforced 6092 Aluminum Composites: I. In Solution

Particulate 6092-T6 Al metal matrix composites (MMCs) reinforced with of , SiC, and exhibited localized corrosion when immersed in a solution exposed to air at room temperature. For the MMCs reinforced with and SiC, the scanning vibrating electrode technique (SVET) revealed that corrosion initiated at localized anodic regions, which transformed into cathodic regions over time. The scanning ion-selective electrode technique (SIET) revealed that the localized anodic regions were acidified, and the localized cathodic regions were alkalinized. The observed anodic-cathodic transformation behavior was attributed to aluminum which has amphoteric oxides, the formation of microcrevices by reinforcement particles left in relief, and the possible galvanic action between the 6092-T6 Al matrix and the and SiC reinforcement particles. The localized anodic and cathodic regions were many times larger than the individual reinforcement particle size. For the -reinforced MMC, localized corrosion coincided with regions showing some cathodic activity and alkalinity. The extent of corrosion of these three MMCs was found to increase with decreasing reinforcement resistivities ρ (i.e., ).

Effect of equal channel angular pressing on strength and ductility of Al–TiAl composites

Severe deformation by equal channel angular pressing (ECAP) of extruded Al–TiAl composites have been studied to understand the influence on the microstructure and mechanical properties as a function of reinforcement particle size and distribution. Microstructure refinement to submicron grain size was already observed in the aluminium matrix after the first ECAP pass, with saturation occurring after four passes. The number of ECAP passes that the composites can sustain before fracturing decreases with the decrease of interparticle spacing, i.e, with an increase in volume fraction of reinforcement particles and/or the decrease in their size. The strength of the composites increases and the ductility decreases after processing by ECAP. The reduction of ductility occurs by weakening of the Al–TiAl interface due to stress concentrations accumulated by the severe deformation of the aluminium matrix.

Influence of Mechanical Milling on the SiC Particulate Size in an Al-SiC Composite

Particle reinforced aluminum-matrix composites are particularly attractive for the automobile and air-craft industries, due to their light weight, high strength, and good wear resistance. In the present work, silicon carbide (SiC) particulates have been incorporated into a pure Al matrix with the help of mechanical milling in a planetary ball-mill. Composite powders were prepared using both raw as well as premilled SiC powders. The effect of milling time on the SiC particulate size was investigated. Systematic analysis of x-ray diffraction data revealed a reinforcement particle size of about 30 nm in a composite containing 50 vol.% SiC. It has been observed that the size reduction occurs at a faster rate when indirect milling is used.

The effect of reinforcement volume fraction and particle size on the mechanical properties of β-tricalcium phosphate–high density polyethylene composites

The mechanical properties of the tricalcium phosphate–high density polyethylene (β-TCP/HDPE) composite samples have been investigated by looking at the effect of particle size and volume fraction of tricalcium phosphate on the fracture strength, modulus of elasticity and failure energy in the composite samples. A decrease in both the fracture strength and failure energy was observed with an increase in the volume fraction of the tricalcium phosphate. Both properties decreased further with the use of larger β-TCP particles. Increase in the tricalcium phosphate content led to an increase in the modulus of elasticity values in the composite samples. However, a lesser increase in modulus of elasticity was observed when larger β-TCP particles were used in the preparation of the composite samples. SEM analysis of the fractured surfaces showed a transition from ductile to brittle type of failure as the volume fraction of the tricalcium phosphate increased in the samples.

The effect of matrix to reinforcement particle size ratio (PSR) on the microstructure and mechanical properties of a P/M processed AlCuMn/SiCp MMC

Abstract Matrix to reinforcement particle size ratio (PSR) is the main factor governing the homogeneity of the reinforcement particle distribution in composites manufactured by the powder metallurgy route. To improve the homogeneity of the distribution, reinforcements with larger average particle size should be used. At the same time, increasing the reinforcement particle size leads to worsening of the mechanical properties due to lower work hardening and higher damage accumulation rates. It is therefore important to optimize the microstructure somewhere in between a smaller reinforcement particle size and a more homogeneous spatial distribution. The effect of PSR on the reinforcement spatial distribution, fabricability, and resulting mechanical properties of a P/M processed AlCuMn/SiC/15p composite was investigated. It was shown that increasing the PSR results in a less-uniform reinforcement distribution, which in turn leads to a decrease in the material fabricability and a general worsening of the mechanical properties. A close to linear dependence of the mechanical properties (yield stress, UTS, elongation before fracture, Young’s modulus) on PSR was found. Tensile elongation shows the highest sensitivity to the worsening of the homogeneity of the reinforcement spatial distribution caused by increasing the PSR. The effect of microstructural homogeneity on the relative change of mechanical properties does not seem to depend on matrix alloy plasticity.

Quantification of particle distribution effects on fatigue in an Al–SiCp composite

Abstract A detailed experimental investigation has been carried out into the effects of particle distribution and morphology on the smooth specimen fatigue behaviour in a powder-processed 2124-based Al–18.7 vol.% silicon carbide particulate (SiCp) composite with a nominal reinforcement particle size of 6.5 μm. Experimental results are reported on the development of fatigue damage in the moderate to high cycle regime, highlighting the role of short crack growth behaviour and the limited initiation life in the materials tested. A methodology is presented for quantitatively analysing the effects of reinforcement spatial distribution and morphology on short crack growth using previously reported finite-body tessellation techniques. Tessellation analysis of the composite has demonstrated that direct crack–tip interactions with the reinforcement particles occurred preferentially in small particle/low volume fraction regions, with further analysis suggesting a controlling influence of particle size on crack path behaviour. In addition, multiple linear regressions of the tessellation data identify a combined influence on growth rates in the ‘discontinuous’ regime of reinforcement clustering and reinforcement morphology (orientation and/or aspect ratio). Results are discussed in relation to known short crack growth mechanics and the microstructural and micromechanical characteristics of particle-reinforced systems.

Quantification of particle distribution effects on fatigue in an Al?SiCp composite

A detailed experimental investigation has been carried out into the effects of particle distribution and morphology on the smooth specimen fatigue behaviour in a powder-processed 2124-based Al–18.7 vol.% silicon carbide particulate (SiC p ) composite with a nominal reinforcement particle size of 6.5 μm. Experimental results are reported on the development of fatigue damage in the moderate to high cycle regime, highlighting the role of short crack growth behaviour and the limited initiation life in the materials tested. A methodology is presented for quantitatively analysing the effects of reinforcement spatial distribution and morphology on short crack growth using previously reported finite-body tessellation techniques. Tessellation analysis of the composite has demonstrated that direct crack–tip interactions with the reinforcement particles occurred preferentially in small particle/low volume fraction regions, with further analysis suggesting a controlling influence of particle size on crack path behaviour. In addition, multiple linear regressions of the tessellation data identify a combined influence on growth rates in the ‘discontinuous’ regime of reinforcement clustering and reinforcement morphology (orientation and/or aspect ratio). Results are discussed in relation to known short crack growth mechanics and the microstructural and micromechanical characteristics of particle-reinforced systems.

Neural network approach to prediction of bending strength and hardening behaviour of particulate reinforced (Al–Si–Mg)-aluminium matrix composites

Abstract In this study, Al 2 O 3 /SiC particulate reinforced (aluminium matrix composites) AMCs, which was produced by using stir casting process, bending strength and hardening behaviour were obtained using a back-propagation neural network that uses gradient descent learning algorithm. First, to prepare the training and test (checking) set of the network, some results were experimentally obtained and recorded in a file on a computer. In the experiments, dual ceramic powder mix was prepared by chemical route then inserted in A332 alloy in melt condition by stir casting process. While SiC particles were supplied commercially, Al 2 O 3 was chemically produced from aluminium sulphate. Al 2 O 3 /SiC powder mix was prepared, and heated up in ceramic crucible in the furnace. Then Al 2 O 3 /SiC ceramic cake was produced [1] . This ceramic cake was milled to adjust particle size before stir casting. This dual ceramic powder with different SiC particle size range was added into liquid matrix alloy. The effect of the reinforcing particle size on bending strength and hardness resistance of Al 2 O 3 /SiC reinforced AMCs was investigated. Mechanical tests showed that bending strength and hardness resistance of 10 vol% Al 2 O 3 /SiC dual ceramic powder composites decrease with increasing reinforced SiC particle size. In neural networks training module, different SiC (μm) particles size range was used as input and bending strength, hardening behaviour and also porous properties in the produced AMCs were used as outputs. Then, the neural network was trained using the prepared training set (also known as learning set). At the end of the training process, the test data were used to check the system accuracy. As a result the neural network was found successful in the prediction of bending strength, hardness behaviour and also porous properties for any given SiC (μm) particles size range in the produced AMCs.

Evaluation of tool wear when machining SiCp-reinforced Al-2014 alloy matrix composites

Abstract SiC p -reinforced metal matrix composites (MMCs) containing two levels of SiC particles (8 and 16 wt%) of different mean particle sizes 30, 45 and 110 μm were prepared using a melt stirring–squeeze casting route. Machining tests were carried out on the composites using uncoated and triple-layer coated carbide cutting tools at various cutting speeds under a constant feed rate and depth of cut. The effects of cutting speed and coating of tool on tool wear were investigated. Furthermore, surface roughness measurements were carried out on the machined surfaces. The reinforcement particle size and its weight fraction together with the cutting speed were found to be the major factors affecting the tool wear. Coated carbide cutting tools performed better than uncoated carbide cutting tools for all the materials machined in terms of tool wear. However, uncoated cutting tools produced better surface finish in terms of mean R a values, particularly at lower cutting speeds. Although the tool wear mechanism remained one of abrasion, detailed examination of the cutting edges under scanning electron microscope (SEM) showed that higher cutting speeds led to edge chipping.